diff options
Diffstat (limited to 'src/compiler/scala/tools/nsc/typechecker/Contexts.scala')
| -rw-r--r-- | src/compiler/scala/tools/nsc/typechecker/Contexts.scala | 1207 |
1 files changed, 895 insertions, 312 deletions
diff --git a/src/compiler/scala/tools/nsc/typechecker/Contexts.scala b/src/compiler/scala/tools/nsc/typechecker/Contexts.scala index 3fe98ed127..82e6de87e3 100644 --- a/src/compiler/scala/tools/nsc/typechecker/Contexts.scala +++ b/src/compiler/scala/tools/nsc/typechecker/Contexts.scala @@ -6,9 +6,9 @@ package scala.tools.nsc package typechecker -import symtab.Flags._ -import scala.collection.mutable.{LinkedHashSet, Set} +import scala.collection.{ immutable, mutable } import scala.annotation.tailrec +import scala.reflect.internal.util.shortClassOfInstance /** * @author Martin Odersky @@ -16,25 +16,35 @@ import scala.annotation.tailrec */ trait Contexts { self: Analyzer => import global._ + import definitions.{ JavaLangPackage, ScalaPackage, PredefModule } + import ContextMode._ - object NoContext extends Context { - outer = this + object NoContext + extends Context(EmptyTree, NoSymbol, EmptyScope, NoCompilationUnit, + null) { // We can't pass the uninitialized `this`. Instead, we treat null specially in `Context#outer` enclClass = this enclMethod = this + override val depth = 0 override def nextEnclosing(p: Context => Boolean): Context = this override def enclosingContextChain: List[Context] = Nil override def implicitss: List[List[ImplicitInfo]] = Nil + override def imports: List[ImportInfo] = Nil + override def firstImport: Option[ImportInfo] = None override def toString = "NoContext" } private object RootImports { - import definitions._ // Possible lists of root imports val javaList = JavaLangPackage :: Nil val javaAndScalaList = JavaLangPackage :: ScalaPackage :: Nil val completeList = JavaLangPackage :: ScalaPackage :: PredefModule :: Nil } + def ambiguousImports(imp1: ImportInfo, imp2: ImportInfo) = + LookupAmbiguous(s"it is imported twice in the same scope by\n$imp1\nand $imp2") + def ambiguousDefnAndImport(owner: Symbol, imp: ImportInfo) = + LookupAmbiguous(s"it is both defined in $owner and imported subsequently by \n$imp") + private lazy val startContext = { NoContext.make( Template(List(), emptyValDef, List()) setSymbol global.NoSymbol setType global.NoType, @@ -42,6 +52,25 @@ trait Contexts { self: Analyzer => rootMirror.RootClass.info.decls) } + private lazy val allUsedSelectors = + mutable.Map[ImportInfo, Set[ImportSelector]]() withDefaultValue Set() + private lazy val allImportInfos = + mutable.Map[CompilationUnit, List[ImportInfo]]() withDefaultValue Nil + + def warnUnusedImports(unit: CompilationUnit) = { + for (imps <- allImportInfos.remove(unit)) { + for (imp <- imps.reverse.distinct) { + val used = allUsedSelectors(imp) + def isMask(s: ImportSelector) = s.name != nme.WILDCARD && s.rename == nme.WILDCARD + + imp.tree.selectors filterNot (s => isMask(s) || used(s)) foreach { sel => + unit.warning(imp posOf sel, "Unused import") + } + } + allUsedSelectors --= imps + } + } + var lastAccessCheckDetails: String = "" /** List of symbols to import from in a root context. Typically that @@ -55,292 +84,360 @@ trait Contexts { self: Analyzer => protected def rootImports(unit: CompilationUnit): List[Symbol] = { assert(definitions.isDefinitionsInitialized, "definitions uninitialized") - if (settings.noimports.value) Nil + if (settings.noimports) Nil else if (unit.isJava) RootImports.javaList - else if (settings.nopredef.value || treeInfo.noPredefImportForUnit(unit.body)) RootImports.javaAndScalaList + else if (settings.nopredef || treeInfo.noPredefImportForUnit(unit.body)) { + debuglog("Omitted import of Predef._ for " + unit) + RootImports.javaAndScalaList + } else RootImports.completeList } - def rootContext(unit: CompilationUnit): Context = rootContext(unit, EmptyTree, false) - def rootContext(unit: CompilationUnit, tree: Tree): Context = rootContext(unit, tree, false) - def rootContext(unit: CompilationUnit, tree: Tree, erasedTypes: Boolean): Context = { - import definitions._ - var sc = startContext - for (sym <- rootImports(unit)) { - sc = sc.makeNewImport(sym) - sc.depth += 1 - } - val c = sc.make(unit, tree, sc.owner, sc.scope, sc.imports) + def rootContext(unit: CompilationUnit, tree: Tree = EmptyTree, erasedTypes: Boolean = false): Context = { + val rootImportsContext = (startContext /: rootImports(unit))((c, sym) => c.make(gen.mkWildcardImport(sym))) + val c = rootImportsContext.make(tree, unit = unit) if (erasedTypes) c.setThrowErrors() else c.setReportErrors() - c.implicitsEnabled = !erasedTypes - c.enrichmentEnabled = c.implicitsEnabled + c(EnrichmentEnabled | ImplicitsEnabled) = !erasedTypes c } def resetContexts() { - var sc = startContext - while (sc != NoContext) { - sc.tree match { - case Import(qual, _) => qual.tpe = singleType(qual.symbol.owner.thisType, qual.symbol) - case _ => + startContext.enclosingContextChain foreach { context => + context.tree match { + case Import(qual, _) => qual setType singleType(qual.symbol.owner.thisType, qual.symbol) + case _ => } - sc.flushAndReturnBuffer() - sc.flushAndReturnWarningsBuffer() - sc = sc.outer + context.reportBuffer.clearAll() } } - private object Errors { - final val ReportErrors = 1 << 0 - final val BufferErrors = 1 << 1 - final val AmbiguousErrors = 1 << 2 - final val notThrowMask = ReportErrors | BufferErrors - final val AllMask = ReportErrors | BufferErrors | AmbiguousErrors - } + /** + * A motley collection of the state and loosely associated behaviour of the type checker. + * Each `Typer` has an associated context, and as it descends into the tree new `(Typer, Context)` + * pairs are spawned. + * + * Meet the crew; first the state: + * + * - A tree, symbol, and scope representing the focus of the typechecker + * - An enclosing context, `outer`. + * - The current compilation unit. + * - A variety of bits that track the current error reporting policy (more on this later); + * whether or not implicits/macros are enabled, whether we are in a self or super call or + * in a constructor suffix. These are represented as bits in the mask `contextMode`. + * - Some odds and ends: undetermined type pararameters of the current line of type inference; + * contextual augmentation for error messages, tracking of the nesting depth. + * + * And behaviour: + * + * - The central point for issuing errors and warnings from the typechecker, with a means + * to buffer these for use in 'silent' type checking, when some recovery might be possible. + * - `Context` is something of a Zipper for the tree were are typechecking: it `enclosingContextChain` + * is the path back to the root. This is exactly what we need to resolve names (`lookupSymbol`) + * and to collect in-scope implicit defintions (`implicitss`) + * Supporting these are `imports`, which represents all `Import` trees in in the enclosing context chain. + * - In a similar vein, we can assess accessiblity (`isAccessible`.) + * + * More on error buffering: + * When are type errors recoverable? In quite a few places, it turns out. Some examples: + * trying to type an application with/without the expected type, or with/without implicit views + * enabled. This is usually mediated by `Typer.silent`, `Inferencer#tryTwice`. + * + * Intially, starting from the `typer` phase, the contexts either buffer or report errors; + * afterwards errors are thrown. This is configured in `rootContext`. Additionally, more + * fine grained control is needed based on the kind of error; ambiguity errors are often + * suppressed during exploraratory typing, such as determining whether `a == b` in an argument + * position is an assignment or a named argument, when `Infererencer#isApplicableSafe` type checks + * applications with and without an expected type, or whtn `Typer#tryTypedApply` tries to fit arguments to + * a function type with/without implicit views. + * + * When the error policies entails error/warning buffering, the mutable [[ReportBuffer]] records + * everything that is issued. It is important to note, that child Contexts created with `make` + * "inherit" the very same `ReportBuffer` instance, whereas children spawned through `makeSilent` + * receive an separate, fresh buffer. + * + * @param tree Tree associated with this context + * @param owner The current owner + * @param scope The current scope + * @param _outer The next outer context. + */ + class Context private[typechecker](val tree: Tree, val owner: Symbol, val scope: Scope, + val unit: CompilationUnit, _outer: Context) { + private def outerIsNoContext = _outer eq null + final def outer: Context = if (outerIsNoContext) NoContext else _outer + + /** The next outer context whose tree is a template or package definition */ + var enclClass: Context = _ - class Context private[typechecker] { - import Errors._ - - var unit: CompilationUnit = NoCompilationUnit - var tree: Tree = _ // Tree associated with this context - var owner: Symbol = NoSymbol // The current owner - var scope: Scope = _ // The current scope - var outer: Context = _ // The next outer context - var enclClass: Context = _ // The next outer context whose tree is a - // template or package definition - @inline final def savingEnclClass[A](c: Context)(a: => A): A = { + @inline private def savingEnclClass[A](c: Context)(a: => A): A = { val saved = enclClass enclClass = c try a finally enclClass = saved } - var enclMethod: Context = _ // The next outer context whose tree is a method - var variance: Int = _ // Variance relative to enclosing class - private var _undetparams: List[Symbol] = List() // Undetermined type parameters, - // not inherited to child contexts - var depth: Int = 0 - var imports: List[ImportInfo] = List() // currently visible imports - var openImplicits: List[OpenImplicit] = List() // types for which implicit arguments - // are currently searched - // for a named application block (Tree) the corresponding NamedApplyInfo + /** A bitmask containing all the boolean flags in a context, e.g. are implicit views enabled */ + var contextMode: ContextMode = ContextMode.DefaultMode + + /** Update all modes in `mask` to `value` */ + def update(mask: ContextMode, value: Boolean) { + contextMode = contextMode.set(value, mask) + } + + /** Set all modes in the mask `enable` to true, and all in `disable` to false. */ + def set(enable: ContextMode = NOmode, disable: ContextMode = NOmode): this.type = { + contextMode = contextMode.set(true, enable).set(false, disable) + this + } + + /** Is this context in all modes in the given `mask`? */ + def apply(mask: ContextMode): Boolean = contextMode.inAll(mask) + + /** The next outer context whose tree is a method */ + var enclMethod: Context = _ + + /** Variance relative to enclosing class */ + var variance: Variance = Variance.Invariant + + private var _undetparams: List[Symbol] = List() + + protected def outerDepth = if (outerIsNoContext) 0 else outer.depth + + val depth: Int = { + val increasesDepth = isRootImport || outerIsNoContext || (outer.scope != scope) + ( if (increasesDepth) 1 else 0 ) + outerDepth + } + + /** The currently visible imports */ + def imports: List[ImportInfo] = outer.imports + /** Equivalent to `imports.headOption`, but more efficient */ + def firstImport: Option[ImportInfo] = outer.firstImport + def isRootImport: Boolean = false + + /** Types for which implicit arguments are currently searched */ + var openImplicits: List[OpenImplicit] = List() + + /* For a named application block (`Tree`) the corresponding `NamedApplyInfo`. */ var namedApplyBlockInfo: Option[(Tree, NamedApplyInfo)] = None var prefix: Type = NoPrefix - var inConstructorSuffix = false // are we in a secondary constructor - // after the this constructor call? - var returnsSeen = false // for method context: were returns encountered? - var inSelfSuperCall = false // is this context (enclosed in) a constructor call? - // (the call to the super or self constructor in the first line of a constructor) - // in this context the object's fields should not be in scope - - var diagnostic: List[String] = Nil // these messages are printed when issuing an error - var implicitsEnabled = false - var macrosEnabled = true - var enrichmentEnabled = false // to selectively allow enrichment in patterns, where other kinds of implicit conversions are not allowed - var checking = false - var retyping = false - - var savedTypeBounds: List[(Symbol, Type)] = List() // saved type bounds - // for type parameters which are narrowed in a GADT + def inConstructorSuffix_=(value: Boolean) = this(ConstructorSuffix) = value + def inConstructorSuffix = this(ConstructorSuffix) + def returnsSeen_=(value: Boolean) = this(ReturnsSeen) = value + def returnsSeen = this(ReturnsSeen) + def inSelfSuperCall_=(value: Boolean) = this(SelfSuperCall) = value + def inSelfSuperCall = this(SelfSuperCall) + def implicitsEnabled_=(value: Boolean) = this(ImplicitsEnabled) = value + def implicitsEnabled = this(ImplicitsEnabled) + def macrosEnabled_=(value: Boolean) = this(MacrosEnabled) = value + def macrosEnabled = this(MacrosEnabled) + def enrichmentEnabled_=(value: Boolean) = this(EnrichmentEnabled) = value + def enrichmentEnabled = this(EnrichmentEnabled) + def checking_=(value: Boolean) = this(Checking) = value + def checking = this(Checking) + def retyping_=(value: Boolean) = this(ReTyping) = value + def retyping = this(ReTyping) + + /** These messages are printed when issuing an error */ + var diagnostic: List[String] = Nil + + /** Saved type bounds for type parameters which are narrowed in a GADT. */ + var savedTypeBounds: List[(Symbol, Type)] = List() + + /** Indentation level, in columns, for output under -Ytyper-debug */ var typingIndentLevel: Int = 0 def typingIndent = " " * typingIndentLevel - var buffer: Set[AbsTypeError] = _ - var warningsBuffer: Set[(Position, String)] = _ - + /** The next enclosing context (potentially `this`) that is owned by a class or method */ def enclClassOrMethod: Context = if ((owner eq NoSymbol) || (owner.isClass) || (owner.isMethod)) this else outer.enclClassOrMethod + /** The next enclosing context (potentially `this`) that has a `CaseDef` as a tree */ + def enclosingCaseDef = nextEnclosing(_.tree.isInstanceOf[CaseDef]) + + /** ...or an Apply. */ + def enclosingApply = nextEnclosing(_.tree.isInstanceOf[Apply]) + + // + // Tracking undetermined type parameters for type argument inference. + // def undetparamsString = if (undetparams.isEmpty) "" else undetparams.mkString("undetparams=", ", ", "") - def undetparams = _undetparams + /** Undetermined type parameters. See `Infer#{inferExprInstance, adjustTypeArgs}`. Not inherited to child contexts */ + def undetparams: List[Symbol] = _undetparams def undetparams_=(ps: List[Symbol]) = { _undetparams = ps } - def extractUndetparams() = { + /** Return and clear the undetermined type parameters */ + def extractUndetparams(): List[Symbol] = { val tparams = undetparams undetparams = List() tparams } - private[this] var mode = 0 - - def errBuffer = buffer - def hasErrors = buffer.nonEmpty - def hasWarnings = warningsBuffer.nonEmpty - - def state: Int = mode - def restoreState(state0: Int) = mode = state0 - - def reportErrors = (state & ReportErrors) != 0 - def bufferErrors = (state & BufferErrors) != 0 - def ambiguousErrors = (state & AmbiguousErrors) != 0 - def throwErrors = (state & notThrowMask) == 0 - - def setReportErrors() = mode = (ReportErrors | AmbiguousErrors) - def setBufferErrors() = { - //assert(bufferErrors || !hasErrors, "When entering the buffer state, context has to be clean. Current buffer: " + buffer) - mode = BufferErrors + /** Run `body` with this context with no undetermined type parameters, restore the original + * the original list afterwards. + * @param reportAmbiguous Should ambiguous errors be reported during evaluation of `body`? + */ + def savingUndeterminedTypeParams[A](reportAmbiguous: Boolean = ambiguousErrors)(body: => A): A = { + withMode() { + this(AmbiguousErrors) = reportAmbiguous + val saved = extractUndetparams() + try body + finally undetparams = saved + } } - def setThrowErrors() = mode &= (~AllMask) - def setAmbiguousErrors(report: Boolean) = if (report) mode |= AmbiguousErrors else mode &= notThrowMask - def updateBuffer(errors: Set[AbsTypeError]) = buffer ++= errors - def condBufferFlush(removeP: AbsTypeError => Boolean) { - val elems = buffer.filter(removeP) - buffer --= elems - } - def flushBuffer() { buffer.clear() } - def flushAndReturnBuffer(): Set[AbsTypeError] = { - val current = buffer.clone() - buffer.clear() - current - } - def flushAndReturnWarningsBuffer(): Set[(Position, String)] = { - val current = warningsBuffer.clone() - warningsBuffer.clear() + // + // Error reporting policies and buffer. + // + + private var _reportBuffer: ReportBuffer = new ReportBuffer + /** A buffer for errors and warnings, used with `this.bufferErrors == true` */ + def reportBuffer = _reportBuffer + /** Discard the current report buffer, and replace with an empty one */ + def useFreshReportBuffer() = _reportBuffer = new ReportBuffer + /** Discard the current report buffer, and replace with `other` */ + def restoreReportBuffer(other: ReportBuffer) = _reportBuffer = other + + /** The first error, if any, in the report buffer */ + def firstError: Option[AbsTypeError] = reportBuffer.firstError + /** Does the report buffer contain any errors? */ + def hasErrors = reportBuffer.hasErrors + + def reportErrors = this(ReportErrors) + def bufferErrors = this(BufferErrors) + def ambiguousErrors = this(AmbiguousErrors) + def throwErrors = contextMode.inNone(ReportErrors | BufferErrors) + + def setReportErrors(): Unit = set(enable = ReportErrors | AmbiguousErrors, disable = BufferErrors) + def setBufferErrors(): Unit = set(enable = BufferErrors, disable = ReportErrors | AmbiguousErrors) + def setThrowErrors(): Unit = this(ReportErrors | AmbiguousErrors | BufferErrors) = false + def setAmbiguousErrors(report: Boolean): Unit = this(AmbiguousErrors) = report + + /** Append the given errors to the report buffer */ + def updateBuffer(errors: Traversable[AbsTypeError]) = reportBuffer ++= errors + /** Clear all errors from the report buffer */ + def flushBuffer() { reportBuffer.clearAllErrors() } + /** Return and clear all errors from the report buffer */ + def flushAndReturnBuffer(): immutable.Seq[AbsTypeError] = { + val current = reportBuffer.errors + reportBuffer.clearAllErrors() current } - def logError(err: AbsTypeError) = buffer += err - - def withImplicitsEnabled[T](op: => T): T = { - val saved = implicitsEnabled - implicitsEnabled = true - try op - finally implicitsEnabled = saved + /** Issue and clear all warnings from the report buffer */ + def flushAndIssueWarnings() { + reportBuffer.warnings foreach { + case (pos, msg) => unit.warning(pos, msg) + } + reportBuffer.clearAllWarnings() } - def withImplicitsDisabled[T](op: => T): T = { - val saved = implicitsEnabled - implicitsEnabled = false - val savedP = enrichmentEnabled - enrichmentEnabled = false + // + // Temporary mode adjustment + // + + @inline def withMode[T](enabled: ContextMode = NOmode, disabled: ContextMode = NOmode)(op: => T): T = { + val saved = contextMode + set(enabled, disabled) try op - finally { - implicitsEnabled = saved - enrichmentEnabled = savedP - } + finally contextMode = saved } - def withImplicitsDisabledAllowEnrichment[T](op: => T): T = { - val saved = implicitsEnabled - implicitsEnabled = false - val savedP = enrichmentEnabled - enrichmentEnabled = true - try op - finally { - implicitsEnabled = saved - enrichmentEnabled = savedP + def withImplicitsEnabled[T](op: => T): T = withMode(enabled = ImplicitsEnabled)(op) + def withImplicitsDisabled[T](op: => T): T = withMode(disabled = ImplicitsEnabled | EnrichmentEnabled)(op) + def withImplicitsDisabledAllowEnrichment[T](op: => T): T = withMode(enabled = EnrichmentEnabled, disabled = ImplicitsEnabled)(op) + def withMacrosEnabled[T](op: => T): T = withMode(enabled = MacrosEnabled)(op) + def withMacrosDisabled[T](op: => T): T = withMode(disabled = MacrosEnabled)(op) + + /** @return true if the `expr` evaluates to true within a silent Context that incurs no errors */ + @inline final def inSilentMode(expr: => Boolean): Boolean = { + withMode() { // withMode with no arguments to restore the mode mutated by `setBufferErrors`. + setBufferErrors() + try expr && !hasErrors + finally reportBuffer.clearAll() } } - def withMacrosEnabled[T](op: => T): T = { - val saved = macrosEnabled - macrosEnabled = true - try op - finally macrosEnabled = saved - } + // + // Child Context Creation + // - def withMacrosDisabled[T](op: => T): T = { - val saved = macrosEnabled - macrosEnabled = false - try op - finally macrosEnabled = saved - } - - def make(unit: CompilationUnit, tree: Tree, owner: Symbol, - scope: Scope, imports: List[ImportInfo]): Context = { - val c = new Context - c.unit = unit - c.tree = tree - c.owner = owner - c.scope = scope - c.outer = this - - tree match { - case Template(_, _, _) | PackageDef(_, _) => - c.enclClass = c - c.prefix = c.owner.thisType - c.inConstructorSuffix = false - case _ => - c.enclClass = this.enclClass - c.prefix = - if (c.owner != this.owner && c.owner.isTerm) NoPrefix - else this.prefix - c.inConstructorSuffix = this.inConstructorSuffix + /** + * Construct a child context. The parent and child will share the report buffer. + * Compare with `makeSilent`, in which the child has a fresh report buffer. + * + * If `tree` is an `Import`, that import will be avaiable at the head of + * `Context#imports`. + */ + def make(tree: Tree = tree, owner: Symbol = owner, + scope: Scope = scope, unit: CompilationUnit = unit): Context = { + val isTemplateOrPackage = tree match { + case _: Template | _: PackageDef => true + case _ => false + } + val isDefDef = tree match { + case _: DefDef => true + case _ => false } - tree match { - case DefDef(_, _, _, _, _, _) => - c.enclMethod = c - case _ => - c.enclMethod = this.enclMethod + val isImport = tree match { + case _: Import => true + case _ => false } - c.variance = this.variance - c.depth = if (scope == this.scope) this.depth else this.depth + 1 - c.imports = imports - c.inSelfSuperCall = inSelfSuperCall - c.restoreState(this.state) - c.diagnostic = this.diagnostic - c.typingIndentLevel = typingIndentLevel - c.implicitsEnabled = this.implicitsEnabled - c.macrosEnabled = this.macrosEnabled - c.enrichmentEnabled = this.enrichmentEnabled - c.checking = this.checking - c.retyping = this.retyping - c.openImplicits = this.openImplicits - c.buffer = if (this.buffer == null) LinkedHashSet[AbsTypeError]() else this.buffer // need to initialize - c.warningsBuffer = if (this.warningsBuffer == null) LinkedHashSet[(Position, String)]() else this.warningsBuffer + val sameOwner = owner == this.owner + val prefixInChild = + if (isTemplateOrPackage) owner.thisType + else if (!sameOwner && owner.isTerm) NoPrefix + else prefix + + // The blank canvas + val c = if (isImport) + new Context(tree, owner, scope, unit, this) with ImportContext + else + new Context(tree, owner, scope, unit, this) + + // Fields that are directly propagated + c.variance = variance + c.diagnostic = diagnostic + c.typingIndentLevel = typingIndentLevel + c.openImplicits = openImplicits + c.contextMode = contextMode // note: ConstructorSuffix, a bit within `mode`, is conditionally overwritten below. + c._reportBuffer = reportBuffer + + // Fields that may take on a different value in the child + c.prefix = prefixInChild + c.enclClass = if (isTemplateOrPackage) c else enclClass + c(ConstructorSuffix) = !isTemplateOrPackage && c(ConstructorSuffix) + c.enclMethod = if (isDefDef) c else enclMethod + registerContext(c.asInstanceOf[analyzer.Context]) debuglog("[context] ++ " + c.unit + " / " + tree.summaryString) c } - // TODO: remove? Doesn't seem to be used - def make(unit: CompilationUnit): Context = { - val c = make(unit, EmptyTree, owner, scope, imports) - c.setReportErrors() - c.implicitsEnabled = true - c.macrosEnabled = true - c - } - - def makeNewImport(sym: Symbol): Context = - makeNewImport(gen.mkWildcardImport(sym)) - - def makeNewImport(imp: Import): Context = - make(unit, imp, owner, scope, new ImportInfo(imp, depth) :: imports) - def make(tree: Tree, owner: Symbol, scope: Scope): Context = + // TODO SI-7345 Moving this optimization into the main overload of `make` causes all tests to fail. + // even if it is extened to check that `unit == this.unit`. Why is this? if (tree == this.tree && owner == this.owner && scope == this.scope) this - else make0(tree, owner, scope) - - private def make0(tree: Tree, owner: Symbol, scope: Scope): Context = - make(unit, tree, owner, scope, imports) + else make(tree, owner, scope, unit) + /** Make a child context that represents a new nested scope */ def makeNewScope(tree: Tree, owner: Symbol): Context = make(tree, owner, newNestedScope(scope)) - // IDE stuff: distinguish between scopes created for typing and scopes created for naming. - def make(tree: Tree, owner: Symbol): Context = - make0(tree, owner, scope) - - def make(tree: Tree): Context = - make(tree, owner) - - def makeSilent(reportAmbiguousErrors: Boolean, newtree: Tree = tree): Context = { + /** Make a child context that buffers errors and warnings into a fresh report buffer. */ + def makeSilent(reportAmbiguousErrors: Boolean = ambiguousErrors, newtree: Tree = tree): Context = { val c = make(newtree) c.setBufferErrors() c.setAmbiguousErrors(reportAmbiguousErrors) - c.buffer = new LinkedHashSet[AbsTypeError]() + c._reportBuffer = new ReportBuffer // A fresh buffer so as not to leak errors/warnings into `this`. c } + /** Make a silent child context does not allow implicits. Used to prevent chaining of implicit views. */ def makeImplicit(reportAmbiguousErrors: Boolean) = { val c = makeSilent(reportAmbiguousErrors) - c.implicitsEnabled = false - c.enrichmentEnabled = false + c(ImplicitsEnabled | EnrichmentEnabled) = false c } @@ -355,12 +452,10 @@ trait Contexts { self: Analyzer => * accessible. */ def makeConstructorContext = { - var baseContext = enclClass.outer - while (baseContext.tree.isInstanceOf[Template]) - baseContext = baseContext.outer + val baseContext = enclClass.outer.nextEnclosing(!_.tree.isInstanceOf[Template]) val argContext = baseContext.makeNewScope(tree, owner) + argContext.contextMode = contextMode argContext.inSelfSuperCall = true - argContext.restoreState(this.state) def enterElems(c: Context) { def enterLocalElems(e: ScopeEntry) { if (e != null && e.owner == c.scope) { @@ -368,7 +463,7 @@ trait Contexts { self: Analyzer => argContext.scope enter e.sym } } - if (c.owner.isTerm && !c.owner.isLocalDummy) { + if (c.isLocal && !c.owner.isLocalDummy) { enterElems(c.outer) enterLocalElems(c.scope.elems) } @@ -379,6 +474,10 @@ trait Contexts { self: Analyzer => argContext } + // + // Error and warning issuance + // + private def addDiagString(msg: String) = { val ds = if (diagnostic.isEmpty) "" @@ -390,19 +489,23 @@ trait Contexts { self: Analyzer => unit.error(pos, if (checking) "\n**** ERROR DURING INTERNAL CHECKING ****\n" + msg else msg) @inline private def issueCommon(err: AbsTypeError)(pf: PartialFunction[AbsTypeError, Unit]) { - debugwarn("issue error: " + err.errMsg) - if (settings.Yissuedebug.value) (new Exception).printStackTrace() + if (settings.Yissuedebug) { + log("issue error: " + err.errMsg) + (new Exception).printStackTrace() + } if (pf isDefinedAt err) pf(err) - else if (bufferErrors) { buffer += err } + else if (bufferErrors) { reportBuffer += err } else throw new TypeError(err.errPos, err.errMsg) } + /** Issue/buffer/throw the given type error according to the current mode for error reporting. */ def issue(err: AbsTypeError) { issueCommon(err) { case _ if reportErrors => unitError(err.errPos, addDiagString(err.errMsg)) } } + /** Issue/buffer/throw the given implicit ambiguity error according to the current mode for error reporting. */ def issueAmbiguousError(pre: Type, sym1: Symbol, sym2: Symbol, err: AbsTypeError) { issueCommon(err) { case _ if ambiguousErrors => if (!pre.isErroneous && !sym1.isErroneous && !sym2.isErroneous) @@ -410,44 +513,31 @@ trait Contexts { self: Analyzer => } } + /** Issue/buffer/throw the given implicit ambiguity error according to the current mode for error reporting. */ def issueAmbiguousError(err: AbsTypeError) { issueCommon(err) { case _ if ambiguousErrors => unitError(err.errPos, addDiagString(err.errMsg)) } } - // TODO remove + /** Issue/throw the given `err` according to the current mode for error reporting. */ def error(pos: Position, err: Throwable) = if (reportErrors) unitError(pos, addDiagString(err.getMessage())) else throw err + /** Issue/throw the given error message according to the current mode for error reporting. */ def error(pos: Position, msg: String) = { val msg1 = addDiagString(msg) if (reportErrors) unitError(pos, msg1) else throw new TypeError(pos, msg1) } - def warning(pos: Position, msg: String): Unit = warning(pos, msg, false) - def warning(pos: Position, msg: String, force: Boolean) { + /** Issue/throw the given error message according to the current mode for error reporting. */ + def warning(pos: Position, msg: String, force: Boolean = false) { if (reportErrors || force) unit.warning(pos, msg) - else if (bufferErrors) warningsBuffer += ((pos, msg)) + else if (bufferErrors) reportBuffer += (pos -> msg) } - def isLocal(): Boolean = tree match { - case Block(_,_) => true - case PackageDef(_, _) => false - case EmptyTree => false - case _ => outer.isLocal() - } - - /** Fast path for some slow checks (ambiguous assignment in Refchecks, and - * existence of __match for MatchTranslation in virtpatmat.) This logic probably - * needs improvement. - */ - def isNameInScope(name: Name) = ( - enclosingContextChain exists (ctx => - (ctx.scope.lookupEntry(name) != null) - || (ctx.owner.rawInfo.member(name) != NoSymbol) - ) - ) + /** Is the owning symbol of this context a term? */ + final def isLocal: Boolean = owner.isTerm // nextOuter determines which context is searched next for implicits // (after `this`, which contributes `newImplicits` below.) In @@ -473,26 +563,35 @@ trait Contexts { self: Analyzer => def enclosingContextChain: List[Context] = this :: outer.enclosingContextChain - override def toString = "Context(%s@%s unit=%s scope=%s errors=%b, reportErrors=%b, throwErrors=%b)".format( - owner.fullName, tree.shortClass, unit, scope.##, hasErrors, reportErrors, throwErrors - ) - /** Is `sub` a subclass of `base` or a companion object of such a subclass? - */ - def isSubClassOrCompanion(sub: Symbol, base: Symbol) = - sub.isNonBottomSubClass(base) || - sub.isModuleClass && sub.linkedClassOfClass.isNonBottomSubClass(base) - - /** Return closest enclosing context that defines a superclass of `clazz`, or a - * companion module of a superclass of `clazz`, or NoContext if none exists */ - def enclosingSuperClassContext(clazz: Symbol): Context = { - var c = this.enclClass - while (c != NoContext && - !clazz.isNonBottomSubClass(c.owner) && - !(c.owner.isModuleClass && clazz.isNonBottomSubClass(c.owner.companionClass))) - c = c.outer.enclClass - c + private def treeTruncated = tree.toString.replaceAll("\\s+", " ").lines.mkString("\\n").take(70) + private def treeIdString = if (settings.uniqid.value) "#" + System.identityHashCode(tree).toString.takeRight(3) else "" + private def treeString = tree match { + case x: Import => "" + x + case Template(parents, `emptyValDef`, body) => + val pstr = if ((parents eq null) || parents.isEmpty) "Nil" else parents mkString " " + val bstr = if (body eq null) "" else body.length + " stats" + s"""Template($pstr, _, $bstr)""" + case x => s"${tree.shortClass}${treeIdString}:${treeTruncated}" } + override def toString = + sm"""|Context($unit) { + | owner = $owner + | tree = $treeString + | scope = ${scope.size} decls + | contextMode = $contextMode + | outer.owner = ${outer.owner} + |}""" + + // + // Accessibility checking + // + + /** Is `sub` a subclass of `base` or a companion object of such a subclass? */ + private def isSubClassOrCompanion(sub: Symbol, base: Symbol) = + sub.isNonBottomSubClass(base) || + sub.isModuleClass && sub.linkedClassOfClass.isNonBottomSubClass(base) + /** Return the closest enclosing context that defines a subclass of `clazz` * or a companion object thereof, or `NoContext` if no such context exists. */ @@ -503,9 +602,7 @@ trait Contexts { self: Analyzer => c } - /** Is `sym` accessible as a member of tree `site` with type - * `pre` in current context? - */ + /** Is `sym` accessible as a member of `pre` in current context? */ def isAccessible(sym: Symbol, pre: Type, superAccess: Boolean = false): Boolean = { lastAccessCheckDetails = "" // Console.println("isAccessible(%s, %s, %s)".format(sym, pre, superAccess)) @@ -518,7 +615,7 @@ trait Contexts { self: Analyzer => (linked ne NoSymbol) && accessWithin(linked) } - /** Are we inside definition of `ab`? */ + /* Are we inside definition of `ab`? */ def accessWithin(ab: Symbol) = { // #3663: we must disregard package nesting if sym isJavaDefined if (sym.isJavaDefined) { @@ -530,26 +627,12 @@ trait Contexts { self: Analyzer => } else (owner hasTransOwner ab) } -/* - var c = this - while (c != NoContext && c.owner != owner) { - if (c.outer eq null) abort("accessWithin(" + owner + ") " + c);//debug - if (c.outer.enclClass eq null) abort("accessWithin(" + owner + ") " + c);//debug - c = c.outer.enclClass - } - c != NoContext - } -*/ - /** Is `clazz` a subclass of an enclosing class? */ - def isSubClassOfEnclosing(clazz: Symbol): Boolean = - enclosingSuperClassContext(clazz) != NoContext - def isSubThisType(pre: Type, clazz: Symbol): Boolean = pre match { case ThisType(pclazz) => pclazz isNonBottomSubClass clazz case _ => false } - /** Is protected access to target symbol permitted */ + /* Is protected access to target symbol permitted */ def isProtectedAccessOK(target: Symbol) = { val c = enclosingSubClassContext(sym.owner) if (c == NoContext) @@ -589,8 +672,7 @@ trait Contexts { self: Analyzer => ( superAccess || pre.isInstanceOf[ThisType] || phase.erasedTypes - || isProtectedAccessOK(sym) - || (sym.allOverriddenSymbols exists isProtectedAccessOK) + || (sym.overrideChain exists isProtectedAccessOK) // that last condition makes protected access via self types work. ) ) @@ -600,26 +682,50 @@ trait Contexts { self: Analyzer => } } + // + // Type bound management + // + def pushTypeBounds(sym: Symbol) { + sym.info match { + case tb: TypeBounds => if (!tb.isEmptyBounds) log(s"Saving $sym info=$tb") + case info => devWarning(s"Something other than a TypeBounds seen in pushTypeBounds: $info is a ${shortClassOfInstance(info)}") + } savedTypeBounds ::= ((sym, sym.info)) } def restoreTypeBounds(tp: Type): Type = { - var current = tp - for ((sym, info) <- savedTypeBounds) { - debuglog("resetting " + sym + " to " + info); - sym.info match { - case TypeBounds(lo, hi) if (hi <:< lo && lo <:< hi) => - current = current.instantiateTypeParams(List(sym), List(lo)) -//@M TODO: when higher-kinded types are inferred, probably need a case PolyType(_, TypeBounds(...)) if ... => - case _ => - } - sym.setInfo(info) + def restore(): Type = savedTypeBounds.foldLeft(tp) { case (current, (sym, savedInfo)) => + def bounds_s(tb: TypeBounds) = if (tb.isEmptyBounds) "<empty bounds>" else s"TypeBounds(lo=${tb.lo}, hi=${tb.hi})" + //@M TODO: when higher-kinded types are inferred, probably need a case PolyType(_, TypeBounds(...)) if ... => + val TypeBounds(lo, hi) = sym.info.bounds + val isUnique = lo <:< hi && hi <:< lo + val isPresent = current contains sym + def saved_s = bounds_s(savedInfo.bounds) + def current_s = bounds_s(sym.info.bounds) + + if (isUnique && isPresent) + devWarningResult(s"Preserving inference: ${sym.nameString}=$hi in $current (based on $current_s) before restoring $sym to saved $saved_s")( + current.instantiateTypeParams(List(sym), List(hi)) + ) + else if (isPresent) + devWarningResult(s"Discarding inferred $current_s because it does not uniquely determine $sym in")(current) + else + logResult(s"Discarding inferred $current_s because $sym does not appear in")(current) + } + try restore() + finally { + for ((sym, savedInfo) <- savedTypeBounds) + sym setInfo debuglogResult(s"Discarding inferred $sym=${sym.info}, restoring saved info")(savedInfo) + + savedTypeBounds = Nil } - savedTypeBounds = List() - current } + // + // Implicit collection + // + private var implicitsCache: List[List[ImplicitInfo]] = null private var implicitsRunId = NoRunId @@ -662,7 +768,7 @@ trait Contexts { self: Analyzer => case ImportSelector(from, _, to, _) :: sels1 => var impls = collect(sels1) filter (info => info.name != from) if (to != nme.WILDCARD) { - for (sym <- imp.importedSymbol(to).alternatives) + for (sym <- importedAccessibleSymbol(imp, to).alternatives) if (isQualifyingImplicit(to, sym, pre, imported = true)) impls = new ImplicitInfo(to, pre, sym) :: impls } @@ -679,6 +785,8 @@ trait Contexts { self: Analyzer => * filtered out later by `eligibleInfos` (SI-4270 / 9129cfe9), as they don't type-check. */ def implicitss: List[List[ImplicitInfo]] = { + val imports = this.imports + val nextOuter = this.nextOuter if (implicitsRunId != currentRunId) { implicitsRunId = currentRunId implicitsCache = List() @@ -695,8 +803,8 @@ trait Contexts { self: Analyzer => } else if (scope != nextOuter.scope && !owner.isPackageClass) { debuglog("collect local implicits " + scope.toList)//DEBUG collectImplicits(scope, NoPrefix) - } else if (imports != nextOuter.imports) { - assert(imports.tail == nextOuter.imports, (imports, nextOuter.imports)) + } else if (firstImport != nextOuter.firstImport) { + assert(imports.tail.headOption == nextOuter.firstImport, (imports, nextOuter.imports)) collectImplicitImports(imports.head) } else if (owner.isPackageClass) { // the corresponding package object may contain implicit members. @@ -708,6 +816,304 @@ trait Contexts { self: Analyzer => implicitsCache } + // + // Imports and symbol lookup + // + + /** It's possible that seemingly conflicting identifiers are + * identifiably the same after type normalization. In such cases, + * allow compilation to proceed. A typical example is: + * package object foo { type InputStream = java.io.InputStream } + * import foo._, java.io._ + */ + private def resolveAmbiguousImport(name: Name, imp1: ImportInfo, imp2: ImportInfo): Option[ImportInfo] = { + val imp1Explicit = imp1 isExplicitImport name + val imp2Explicit = imp2 isExplicitImport name + val ambiguous = if (imp1.depth == imp2.depth) imp1Explicit == imp2Explicit else !imp1Explicit && imp2Explicit + val imp1Symbol = (imp1 importedSymbol name).initialize filter (s => isAccessible(s, imp1.qual.tpe, superAccess = false)) + val imp2Symbol = (imp2 importedSymbol name).initialize filter (s => isAccessible(s, imp2.qual.tpe, superAccess = false)) + + // The types of the qualifiers from which the ambiguous imports come. + // If the ambiguous name is a value, these must be the same. + def t1 = imp1.qual.tpe + def t2 = imp2.qual.tpe + // The types of the ambiguous symbols, seen as members of their qualifiers. + // If the ambiguous name is a monomorphic type, we can relax this far. + def mt1 = t1 memberType imp1Symbol + def mt2 = t2 memberType imp2Symbol + + def characterize = List( + s"types: $t1 =:= $t2 ${t1 =:= t2} members: ${mt1 =:= mt2}", + s"member type 1: $mt1", + s"member type 2: $mt2" + ).mkString("\n ") + + if (!ambiguous || !imp2Symbol.exists) Some(imp1) + else if (!imp1Symbol.exists) Some(imp2) + else ( + // The symbol names are checked rather than the symbols themselves because + // each time an overloaded member is looked up it receives a new symbol. + // So foo.member("x") != foo.member("x") if x is overloaded. This seems + // likely to be the cause of other bugs too... + if (t1 =:= t2 && imp1Symbol.name == imp2Symbol.name) { + log(s"Suppressing ambiguous import: $t1 =:= $t2 && $imp1Symbol == $imp2Symbol") + Some(imp1) + } + // Monomorphism restriction on types is in part because type aliases could have the + // same target type but attach different variance to the parameters. Maybe it can be + // relaxed, but doesn't seem worth it at present. + else if (mt1 =:= mt2 && name.isTypeName && imp1Symbol.isMonomorphicType && imp2Symbol.isMonomorphicType) { + log(s"Suppressing ambiguous import: $mt1 =:= $mt2 && $imp1Symbol and $imp2Symbol are equivalent") + Some(imp1) + } + else { + log(s"Import is genuinely ambiguous:\n " + characterize) + None + } + ) + } + + /** The symbol with name `name` imported via the import in `imp`, + * if any such symbol is accessible from this context. + */ + def importedAccessibleSymbol(imp: ImportInfo, name: Name): Symbol = + importedAccessibleSymbol(imp, name, requireExplicit = false) + + private def importedAccessibleSymbol(imp: ImportInfo, name: Name, requireExplicit: Boolean): Symbol = + imp.importedSymbol(name, requireExplicit) filter (s => isAccessible(s, imp.qual.tpe, superAccess = false)) + + /** Is `sym` defined in package object of package `pkg`? + * Since sym may be defined in some parent of the package object, + * we cannot inspect its owner only; we have to go through the + * info of the package object. However to avoid cycles we'll check + * what other ways we can before pushing that way. + */ + def isInPackageObject(sym: Symbol, pkg: Symbol): Boolean = { + def uninitialized(what: String) = { + log(s"Cannot look for $sym in package object of $pkg; $what is not initialized.") + false + } + def pkgClass = if (pkg.isTerm) pkg.moduleClass else pkg + def matchesInfo = ( + // need to be careful here to not get a cyclic reference during bootstrap + if (pkg.isInitialized) { + val module = pkg.info member nme.PACKAGEkw + if (module.isInitialized) + module.info.member(sym.name).alternatives contains sym + else + uninitialized("" + module) + } + else uninitialized("" + pkg) + ) + def inPackageObject(sym: Symbol) = ( + // To be in the package object, one of these must be true: + // 1) sym.owner is a package object class, and sym.owner.owner is the package class for `pkg` + // 2) sym.owner is inherited by the correct package object class + // We try to establish 1) by inspecting the owners directly, and then we try + // to rule out 2), and only if both those fail do we resort to looking in the info. + !sym.isPackage && (sym.owner ne NoSymbol) && ( + if (sym.owner.isPackageObjectClass) + sym.owner.owner == pkgClass + else + !sym.owner.isPackageClass && matchesInfo + ) + ) + + // An overloaded symbol might not have the expected owner! + // The alternatives must be inspected directly. + pkgClass.isPackageClass && ( + if (sym.isOverloaded) + sym.alternatives forall (isInPackageObject(_, pkg)) + else + inPackageObject(sym) + ) + } + + def isNameInScope(name: Name) = lookupSymbol(name, _ => true).isSuccess + + /** Find the symbol of a simple name starting from this context. + * All names are filtered through the "qualifies" predicate, + * the search continuing as long as no qualifying name is found. + */ + def lookupSymbol(name: Name, qualifies: Symbol => Boolean): NameLookup = { + var lookupError: NameLookup = null // set to non-null if a definite error is encountered + var inaccessible: NameLookup = null // records inaccessible symbol for error reporting in case none is found + var defSym: Symbol = NoSymbol // the directly found symbol + var pre: Type = NoPrefix // the prefix type of defSym, if a class member + var cx: Context = this // the context under consideration + var symbolDepth: Int = -1 // the depth of the directly found symbol + + def finish(qual: Tree, sym: Symbol): NameLookup = ( + if (lookupError ne null) lookupError + else sym match { + case NoSymbol if inaccessible ne null => inaccessible + case NoSymbol => LookupNotFound + case _ => LookupSucceeded(qual, sym) + } + ) + def finishDefSym(sym: Symbol, pre0: Type): NameLookup = + if (requiresQualifier(sym)) + finish(gen.mkAttributedQualifier(pre0), sym) + else + finish(EmptyTree, sym) + + def isPackageOwnedInDifferentUnit(s: Symbol) = ( + s.isDefinedInPackage && ( + !currentRun.compiles(s) + || unit.exists && s.sourceFile != unit.source.file + ) + ) + def requiresQualifier(s: Symbol) = ( + s.owner.isClass + && !s.owner.isPackageClass + && !s.isTypeParameterOrSkolem + ) + def lookupInPrefix(name: Name) = pre member name filter qualifies + def accessibleInPrefix(s: Symbol) = isAccessible(s, pre, superAccess = false) + + def searchPrefix = { + cx = cx.enclClass + val found0 = lookupInPrefix(name) + val found1 = found0 filter accessibleInPrefix + if (found0.exists && !found1.exists && inaccessible == null) + inaccessible = LookupInaccessible(found0, analyzer.lastAccessCheckDetails) + + found1 + } + + def lookupInScope(scope: Scope) = + (scope lookupUnshadowedEntries name filter (e => qualifies(e.sym))).toList + + def newOverloaded(owner: Symbol, pre: Type, entries: List[ScopeEntry]) = + logResult(s"!!! lookup overloaded")(owner.newOverloaded(pre, entries map (_.sym))) + + // Constructor lookup should only look in the decls of the enclosing class + // not in the self-type, nor in the enclosing context, nor in imports (SI-4460, SI-6745) + if (name == nme.CONSTRUCTOR) return { + val enclClassSym = cx.enclClass.owner + val scope = cx.enclClass.prefix.baseType(enclClassSym).decls + val constructorSym = lookupInScope(scope) match { + case Nil => NoSymbol + case hd :: Nil => hd.sym + case entries => newOverloaded(enclClassSym, cx.enclClass.prefix, entries) + } + finishDefSym(constructorSym, cx.enclClass.prefix) + } + + // cx.scope eq null arises during FixInvalidSyms in Duplicators + while (defSym == NoSymbol && (cx ne NoContext) && (cx.scope ne null)) { + pre = cx.enclClass.prefix + defSym = lookupInScope(cx.scope) match { + case Nil => searchPrefix + case entries @ (hd :: tl) => + // we have a winner: record the symbol depth + symbolDepth = (cx.depth - cx.scope.nestingLevel) + hd.depth + if (tl.isEmpty) hd.sym + else newOverloaded(cx.owner, pre, entries) + } + if (!defSym.exists) + cx = cx.outer // push further outward + } + if (symbolDepth < 0) + symbolDepth = cx.depth + + var impSym: Symbol = NoSymbol + var imports = Context.this.imports + def imp1 = imports.head + def imp2 = imports.tail.head + def sameDepth = imp1.depth == imp2.depth + def imp1Explicit = imp1 isExplicitImport name + def imp2Explicit = imp2 isExplicitImport name + + def lookupImport(imp: ImportInfo, requireExplicit: Boolean) = + importedAccessibleSymbol(imp, name, requireExplicit) filter qualifies + + // Java: A single-type-import declaration d in a compilation unit c of package p + // that imports a type named n shadows, throughout c, the declarations of: + // + // 1) any top level type named n declared in another compilation unit of p + // + // A type-import-on-demand declaration never causes any other declaration to be shadowed. + // + // Scala: Bindings of different kinds have a precedence defined on them: + // + // 1) Definitions and declarations that are local, inherited, or made available by a + // package clause in the same compilation unit where the definition occurs have + // highest precedence. + // 2) Explicit imports have next highest precedence. + def depthOk(imp: ImportInfo) = ( + imp.depth > symbolDepth + || (unit.isJava && imp.isExplicitImport(name) && imp.depth == symbolDepth) + ) + + while (!impSym.exists && imports.nonEmpty && depthOk(imports.head)) { + impSym = lookupImport(imp1, requireExplicit = false) + if (!impSym.exists) + imports = imports.tail + } + + if (defSym.exists && impSym.exists) { + // imported symbols take precedence over package-owned symbols in different compilation units. + if (isPackageOwnedInDifferentUnit(defSym)) + defSym = NoSymbol + // Defined symbols take precedence over erroneous imports. + else if (impSym.isError || impSym.name == nme.CONSTRUCTOR) + impSym = NoSymbol + // Otherwise they are irreconcilably ambiguous + else + return ambiguousDefnAndImport(defSym.owner, imp1) + } + + // At this point only one or the other of defSym and impSym might be set. + if (defSym.exists) + finishDefSym(defSym, pre) + else if (impSym.exists) { + // We continue walking down the imports as long as the tail is non-empty, which gives us: + // imports == imp1 :: imp2 :: _ + // And at least one of the following is true: + // - imp1 and imp2 are at the same depth + // - imp1 is a wildcard import, so all explicit imports from outer scopes must be checked + def keepLooking = ( + lookupError == null + && imports.tail.nonEmpty + && (sameDepth || !imp1Explicit) + ) + // If we find a competitor imp2 which imports the same name, possible outcomes are: + // + // - same depth, imp1 wild, imp2 explicit: imp2 wins, drop imp1 + // - same depth, imp1 wild, imp2 wild: ambiguity check + // - same depth, imp1 explicit, imp2 explicit: ambiguity check + // - differing depth, imp1 wild, imp2 explicit: ambiguity check + // - all others: imp1 wins, drop imp2 + // + // The ambiguity check is: if we can verify that both imports refer to the same + // symbol (e.g. import foo.X followed by import foo._) then we discard imp2 + // and proceed. If we cannot, issue an ambiguity error. + while (keepLooking) { + // If not at the same depth, limit the lookup to explicit imports. + // This is desirable from a performance standpoint (compare to + // filtering after the fact) but also necessary to keep the unused + // import check from being misled by symbol lookups which are not + // actually used. + val other = lookupImport(imp2, requireExplicit = !sameDepth) + def imp1wins() = { imports = imp1 :: imports.tail.tail } + def imp2wins() = { impSym = other ; imports = imports.tail } + + if (!other.exists) // imp1 wins; drop imp2 and continue. + imp1wins() + else if (sameDepth && !imp1Explicit && imp2Explicit) // imp2 wins; drop imp1 and continue. + imp2wins() + else resolveAmbiguousImport(name, imp1, imp2) match { + case Some(imp) => if (imp eq imp1) imp1wins() else imp2wins() + case _ => lookupError = ambiguousImports(imp1, imp2) + } + } + // optimization: don't write out package prefixes + finish(resetPos(imp1.qual.duplicate), impSym) + } + else finish(EmptyTree, NoSymbol) + } + /** * Find a symbol in this context or one of its outers. * @@ -731,12 +1137,84 @@ trait Contexts { self: Analyzer => } } //class Context + /** A `Context` focussed on an `Import` tree */ + trait ImportContext extends Context { + private val impInfo: ImportInfo = { + val info = new ImportInfo(tree.asInstanceOf[Import], outerDepth) + if (settings.lint && !isRootImport) // excludes java.lang/scala/Predef imports + allImportInfos(unit) ::= info + info + } + override final def imports = impInfo :: super.imports + override final def firstImport = Some(impInfo) + override final def isRootImport = !tree.pos.isDefined + override final def toString = s"ImportContext { $impInfo; outer.owner = ${outer.owner} }" + } + + /** A buffer for warnings and errors that are accumulated during speculative type checking. */ + final class ReportBuffer { + type Error = AbsTypeError + type Warning = (Position, String) + + private def newBuffer[A] = mutable.LinkedHashSet.empty[A] // Important to use LinkedHS for stable results. + + // [JZ] Contexts, pre- the SI-7345 refactor, avoided allocating the buffers until needed. This + // is replicated here out of conservatism. + private var _errorBuffer: mutable.LinkedHashSet[Error] = _ + private def errorBuffer = {if (_errorBuffer == null) _errorBuffer = newBuffer; _errorBuffer} + def errors: immutable.Seq[Error] = errorBuffer.toVector + + private var _warningBuffer: mutable.LinkedHashSet[Warning] = _ + private def warningBuffer = {if (_warningBuffer == null) _warningBuffer = newBuffer; _warningBuffer} + def warnings: immutable.Seq[Warning] = warningBuffer.toVector + + def +=(error: AbsTypeError): this.type = { + errorBuffer += error + this + } + def ++=(errors: Traversable[AbsTypeError]): this.type = { + errorBuffer ++= errors + this + } + def +=(warning: Warning): this.type = { + warningBuffer += warning + this + } + + def clearAll(): this.type = { + clearAllErrors(); clearAllWarnings(); + } + + def clearAllErrors(): this.type = { + errorBuffer.clear() + this + } + def clearErrors(removeF: PartialFunction[AbsTypeError, Boolean]): this.type = { + errorBuffer.retain(!PartialFunction.cond(_)(removeF)) + this + } + def retainErrors(leaveF: PartialFunction[AbsTypeError, Boolean]): this.type = { + errorBuffer.retain(PartialFunction.cond(_)(leaveF)) + this + } + def clearAllWarnings(): this.type = { + warningBuffer.clear() + this + } + + def hasErrors = errorBuffer.nonEmpty + def firstError = errorBuffer.headOption + } + class ImportInfo(val tree: Import, val depth: Int) { + def pos = tree.pos + def posOf(sel: ImportSelector) = tree.pos withPoint sel.namePos + /** The prefix expression */ def qual: Tree = tree.symbol.info match { case ImportType(expr) => expr - case ErrorType => tree setType NoType // fix for #2870 - case _ => throw new FatalError("symbol " + tree.symbol + " has bad type: " + tree.symbol.info) //debug + case ErrorType => tree setType NoType // fix for #2870 + case _ => throw new FatalError("symbol " + tree.symbol + " has bad type: " + tree.symbol.info) //debug } /** Is name imported explicitly, not via wildcard? */ @@ -745,25 +1223,53 @@ trait Contexts { self: Analyzer => /** The symbol with name `name` imported from import clause `tree`. */ - def importedSymbol(name: Name): Symbol = { + def importedSymbol(name: Name): Symbol = importedSymbol(name, requireExplicit = false) + + private def recordUsage(sel: ImportSelector, result: Symbol) { + def posstr = pos.source.file.name + ":" + posOf(sel).safeLine + def resstr = if (tree.symbol.hasCompleteInfo) s"(qual=$qual, $result)" else s"(expr=${tree.expr}, ${result.fullLocationString})" + debuglog(s"In $this at $posstr, selector '${selectorString(sel)}' resolved to $resstr") + allUsedSelectors(this) += sel + } + + /** If requireExplicit is true, wildcard imports are not considered. */ + def importedSymbol(name: Name, requireExplicit: Boolean): Symbol = { var result: Symbol = NoSymbol var renamed = false var selectors = tree.selectors - while (selectors != Nil && result == NoSymbol) { - if (selectors.head.rename == name.toTermName) + def current = selectors.head + while (selectors.nonEmpty && result == NoSymbol) { + if (current.rename == name.toTermName) result = qual.tpe.nonLocalMember( // new to address #2733: consider only non-local members for imports - if (name.isTypeName) selectors.head.name.toTypeName else selectors.head.name) - else if (selectors.head.name == name.toTermName) + if (name.isTypeName) current.name.toTypeName else current.name) + else if (current.name == name.toTermName) renamed = true - else if (selectors.head.name == nme.WILDCARD && !renamed) + else if (current.name == nme.WILDCARD && !renamed && !requireExplicit) result = qual.tpe.nonLocalMember(name) - selectors = selectors.tail + + if (result == NoSymbol) + selectors = selectors.tail } - result + if (settings.lint && selectors.nonEmpty && result != NoSymbol && pos != NoPosition) + recordUsage(current, result) + + // Harden against the fallout from bugs like SI-6745 + // + // [JZ] I considered issuing a devWarning and moving the + // check inside the above loop, as I believe that + // this always represents a mistake on the part of + // the caller. + if (definitions isImportable result) result + else NoSymbol + } + private def selectorString(s: ImportSelector): String = { + if (s.name == nme.WILDCARD && s.rename == null) "_" + else if (s.name == s.rename) "" + s.name + else s.name + " => " + s.rename } def allImportedSymbols: Iterable[Symbol] = - qual.tpe.members flatMap (transformImport(tree.selectors, _)) + importableMembers(qual.tpe) flatMap (transformImport(tree.selectors, _)) private def transformImport(selectors: List[ImportSelector], sym: Symbol): List[Symbol] = selectors match { case List() => List() @@ -774,10 +1280,87 @@ trait Contexts { self: Analyzer => case _ :: rest => transformImport(rest, sym) } - override def toString() = tree.toString() + override def hashCode = tree.## + override def equals(other: Any) = other match { + case that: ImportInfo => (tree == that.tree) + case _ => false + } + override def toString = tree.toString } case class ImportType(expr: Tree) extends Type { override def safeToString = "ImportType("+expr+")" } } + +object ContextMode { + private implicit def liftIntBitsToContextState(bits: Int): ContextMode = apply(bits) + def apply(bits: Int): ContextMode = new ContextMode(bits) + final val NOmode: ContextMode = 0 + + final val ReportErrors: ContextMode = 1 << 0 + final val BufferErrors: ContextMode = 1 << 1 + final val AmbiguousErrors: ContextMode = 1 << 2 + + /** Are we in a secondary constructor after the this constructor call? */ + final val ConstructorSuffix: ContextMode = 1 << 3 + + /** For method context: were returns encountered? */ + final val ReturnsSeen: ContextMode = 1 << 4 + + /** Is this context (enclosed in) a constructor call? + * (the call to the super or self constructor in the first line of a constructor.) + * In such a context, the object's fields should not be in scope + */ + final val SelfSuperCall: ContextMode = 1 << 5 + + // TODO harvest documentation for this + final val ImplicitsEnabled: ContextMode = 1 << 6 + + final val MacrosEnabled: ContextMode = 1 << 7 + + /** To selectively allow enrichment in patterns, where other kinds of implicit conversions are not allowed */ + final val EnrichmentEnabled: ContextMode = 1 << 8 + + /** Are we in a run of [[scala.tools.nsc.typechecker.TreeCheckers]]? */ + final val Checking: ContextMode = 1 << 9 + + /** Are we retypechecking arguments independently from the function applied to them? See `Typer.tryTypedApply` */ + // TODO This seems to directly overlap with Mode.SNDTRYmode + final val ReTyping: ContextMode = 1 << 10 + + final val DefaultMode: ContextMode = MacrosEnabled + + private val contextModeNameMap = Map( + ReportErrors -> "ReportErrors", + BufferErrors -> "BufferErrors", + AmbiguousErrors -> "AmbiguousErrors", + ConstructorSuffix -> "ConstructorSuffix", + SelfSuperCall -> "SelfSuperCall", + ImplicitsEnabled -> "ImplicitsEnabled", + MacrosEnabled -> "MacrosEnabled", + Checking -> "Checking", + ReTyping -> "ReTyping" + ) +} + +/** + * A value class to carry the boolean flags of a context, such as whether errors should + * be buffered or reported. + */ +final class ContextMode private (val bits: Int) extends AnyVal { + import ContextMode._ + + def &(other: ContextMode): ContextMode = new ContextMode(bits & other.bits) + def |(other: ContextMode): ContextMode = new ContextMode(bits | other.bits) + def &~(other: ContextMode): ContextMode = new ContextMode(bits & ~(other.bits)) + def set(value: Boolean, mask: ContextMode) = if (value) |(mask) else &~(mask) + + def inAll(required: ContextMode) = (this & required) == required + def inAny(required: ContextMode) = (this & required) != NOmode + def inNone(prohibited: ContextMode) = (this & prohibited) == NOmode + + override def toString = + if (bits == 0) "NOmode" + else (contextModeNameMap filterKeys inAll).values.toList.sorted mkString " " +} |